Ok so I was sat playing on my ps4 this evening and while airing for a game to load I decided to check something on the internet using my phone. As the game started I closed the internet and placed my phone on the sofa with the screen still on. After about a minute, my phone made a noise (a bit like a ring tone or reminder tone). Nothing appeared on the screen, no message in the tab at the top, nothing. Continued for a few seconds then stopped. It wasn't a tone that I recognised ie not my ring tone etc. anyone else had this? Any ideas why?